JavaScript - String

JavaScript - String

Introduction In JavaScript, a string is a sequence of characters enclosed within single quotes ('') or double quotes (""). Strings are used to store and manipulate text-based data. This documentation provides an overview of common operations and methods used to work with strings in JavaScript.

Creating a String Strings can be created in JavaScript using the string literal or the String constructor.

• String Literal:

javascript
let message = 'Hello, World!';

• String Constructor:

javascript
let message = new String('Hello, World!');

Accessing Characters Individual characters within a string can be accessed using square brackets [] and the character's index position. Note that string indices start at 0.

javascript
let message = 'Hello, World!';
console.log(message[0]);  // Output: 'H'

String Length The length property returns the number of characters in a string.

javascript
let message = 'Hello, World!';
console.log(message.length);  // Output: 13

Concatenation Strings can be concatenated (joined) using the plus (+) operator or the concat() method.

• Using the plus operator:

javascript
let greeting = 'Hello';
let name = 'John';
let message = greeting + ', ' + name + '!';
console.log(message);  // Output: 'Hello, John!'

• Using the concat() method:

javascript
let greeting = 'Hello';
let name = 'John';
let message = greeting.concat(', ', name, '!');
console.log(message);  // Output: 'Hello, John!'

String Methods JavaScript provides various methods to perform operations on strings. Here are some commonly used methods:

• toUpperCase() and toLowerCase(): Converts a string to uppercase or lowercase.
• trim(): Removes whitespace from the beginning and end of a string.
• charAt(): Returns the character at a specified index.
• substring(): Extracts a portion of a string between two indices.
• indexOf(): Returns the index of the first occurrence of a specified substring.
• replace(): Replaces a substring with another substring.
• split(): Splits a string into an array of substrings based on a specified separator.

javascript
let message = 'Hello, World!';

console.log(message.toUpperCase());    // Output: 'HELLO, WORLD!'
console.log(message.toLowerCase());    // Output: 'hello, world!'
console.log(message.trim());           // Output: 'Hello, World!'
console.log(message.charAt(7));        // Output: 'W'
console.log(message.substring(7, 12)); // Output: 'World'
console.log(message.indexOf('o'));     // Output: 4
console.log(message.replace('Hello', 'Hi'));  // Output: 'Hi, World!'
console.log(message.split(','));       // Output: ['Hello', ' World!']

String Template Literals Template literals provide an elegant way to embed expressions within strings, allowing variables and expressions to be evaluated and interpolated.

javascript
let name = 'John';
let age = 30;

let message = `My name is ${name} and I am ${age} years old.`;
console.log(message);  // Output: 'My name is John and I am 30 years old.'

These are just some of the basic concepts and methods related to strings in JavaScript. Strings are a fundamental part of JavaScript, and understanding how to work with them is essential for any JavaScript developer.